Identification of the genes associated with pathogenicity in Aspergillus species: Aspergillus is one of the serious opportunistic fungal pathogens that cause systemic infection in immunocompromised patients especially those with prolonged neutropenia and chronic granulomatous disease of childhood (CGD). Aspergillosis is caused by inhalation of conidia. The most important pathogenic species of aspergillus produce conidia with greenish-blue to green conidia with a hydrophobic surface. Since the pigment represents an important surface component of Aspergillus conidia that interacts with host upon inhalation, we have focused on the genes involved in biosynthesis of conidial pigment. In the previous year, we have cloned the APR1 gene encoding a greenish-blue pigment in spores of Aspergillus fumigatus that modulates complement activation. This year we have characterized the APR1 gene and its product as scytalone dehydratase which is involved in 1,8-dihydroxynaphthalene (DHN) melanin synthesis. Furthermore , we identified another gene, APR2, which is nvolved in the biosynthesis of DHN melanin and investigated the effects of the two gene mutations on both pigmentation and complement deposition. The genes APR1 and APR2 are closely linked and both are involved in conidial pigment biosynthesis in A. fumigatus and modulate C3 binding on conidial surface.